Bone instrumentation cover or shield

ABSTRACT

A bone instrumentation cover or shield has a hollow cap or casing for encapsulating projecting parts of instrumentation installed in a bone, and a fastener portion for securing it to the bone or to parts of the instrumentation. The instrumentation shield or cover is made of medically safe material, in various sizes, and may be a rigid casing or pliable, stretchable, or adaptable with slidable, displaceable or pleated panels to provide a medically safe physical barrier between projecting parts of bone instrumentation constructs and surrounding bone and soft tissues, in order to minimize local irritation or injury and to provide a barrier to ingrowth from bone and/or fibrous tissues. The cap or casing is readily applied over the instrumentation, then cinched, tied or fastened to the instrumentation or adjacent areas.

CROSS-REFERENCE TO RELATED APPLICATION

This United States Non-Provisional Patent Application is a ContinuationApplication of U.S. patent application Ser. 10/634,368, filed Aug. 6,2003, entitled “Bone Instrumentation Cover or Shield,” the disclosuresof which are incorporated by reference in their entirety.

FIELD OF THE INVENTION

This invention generally relates to a device used in protect the bodyand the instrumentation installed in bone during spinal orreconstructive surgery, and particularly to a bone instrumentation coveror shield.

BACKGROUND OF INVENTION

Spinal bone deterioration, disc rupture, degenerative disc disease ordeformity is surgically correctable by installing a rod secured topedicle screws mounted into good bone in order to support or reinforcethe deteriorated, weakened, or deformed area.

However, the presence of instrumentation installed in bone can presentproblems for the patient. Projecting parts of the instrumentation canirritate and cause swelling or injury to the surrounding tissues.Ingrowth of bone or fibrous tissue into parts of the instrumentation ispossible if the bone or tissue regenerates, causing possibleinterference with the function of the instrumentation or perhaps makingit difficult to later remove the instrumentation if it is no longerneeded or if a next progressive stage of instrumentation is required.Many of the systems in use tend to be fairly bulky and frequently leadto problems within patients. Bursae may form which can lead to pain andpossible skin necrosis and breakdown. Removing the instrumentation mayultimately be necessary in such cases. It is therefore desirable toprovide a way to protect the body and the instrumentation installed inbone during spinal or reconstructive surgery.

SUMMARY OF INVENTION

In accordance with the present invention, a bone instrumentation coveror shield comprises a cap or casing which is dimensioned to be placedover and to encapsulate projecting parts of instrumentation installed ina bone, and a fastener portion provided at a lower edge of the cap orcasing for securing it to the bone or to parts of the instrumentationwhere it is installed in the bone. The cap or casing is shaped anddimensioned to fit over the projecting parts of the instrumentation. Thefastener portion is designed to attach and hold the cap or casing to thebone or to parts of the instrumentation installed in the bone.

In one preferred embodiment, the cover or shield is formed with a hollowcap or casing in a suitable shape such as a three-dimensional oval orparallelpiped for fitting over the projecting parts of theinstrumentation, and has a lower frame with a toothed-edge bottom forlocking on to the parts of the instrumentation that are mounted into thebone (pedicle screws). The fastener can include pre-loaded sutures forattachment to the bone or to adjacent parts of the instrumentation.

In another preferred embodiment, the cover or shield is formed with ahollow cap or casing as described above, and a lower frame is providedwith an aperture to accommodate parts of the instrumentation that extendthere from to where they are mounted into or fastened to the bone.

In a further embodiment, the cap or casing is formed as a pliable orflexible pouch, and the fastener portion is formed by one or moredrawstrings for cinching the lower edge of the pouch opening around theparts of the instrumentation mounted into or fastened to the bone. Theextra lengths of the drawstrings may be fastened to the bone orinstrumentation like the sutures described above.

In yet another embodiment, the cap or casing is formed as a pliable orflexible sheath, and the fastener portion is formed by a lower cinchring having openings therein for threading through a number of suturestrings for tightening the cap vertically down to the cinch ring overthe instrumentation, and one or more drawstrings in the cinch ring fortightening horizontally around the instrumentation.

In still another embodiment, the cap or casing is formed with slidableor displaceable panels or with pleats, for adjustment of its length,width, or height snugly around the instrumentation.

Other objects, features, and advantages of the present invention will beexplained in the following detailed description of the invention havingreference to the appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic drawing of a first embodiment of the inventionhaving a cover or shield formed with a hollow cap or casing and a lowerframe with a toothed-edge bottom for locking on to instrumentationmounted into the bone.

FIG. 2 is a schematic drawing of a second embodiment in which the coveror shield is formed with a hollow cap or casing and a lower frame withan aperture for the instrumentation.

FIGS. 3A and 3B are schematic drawings of a third embodiment in whichthe cover or shield is a pliable or flexible pouch, and the fastenerportion has drawstrings for cinching around the instrumentation.

FIG. 4 is a schematic drawing of a fourth embodiment in which the coveror shield is formed with a cap, and the fastener portion is formed by alower cinch ring threaded with a number of suture strings for tighteningthe cap vertically down to the cinch ring, and drawstrings fortightening the cinch ring horizontally around the instrumentation.

FIG. 5 is a schematic drawing of a fifth embodiment in which the coveror shield has slidable or displaceable panels for adjustment of itslength, width, or height around the instrumentation.

DETAILED DESCRIPTION OF INVENTION

Referring to FIG. 1, a first embodiment of the instrumentation cover orshield in accordance with the present invention is formed with a hollowcap or casing 10 and a lower frame 10 a formed with a toothed-edgebottom for locking onto instrumentation, i.e., pedicle screws 12 havingscrew-threaded lower portions which are mounted into the bone or bonesof the patient. A rod 14 is secured through the post portions of thepedicles 12 to provide rigid instrumentation support across a given areaof the bone. When the instrumentation has been mounted into the bone ina surgical procedure, the parts projecting above the bone can causeirritation of injury to surrounding bones or tissues. The cover casing10 is designed and dimensioned to encapsulate the projecting parts toprevent irritation or injury. The cover is applied from the dorsalaspect, inserting the longitudinal rod and pedicle screw ends throughthe mid-line aperture, then using the toothed edges of the lower frame10 a to lock onto the lower parts of the pedicle screw 12 adjacent wherethey enter the bone. The toothed edge has teeth spacings for lockingonto the projecting stems of the pedicle screw. Sutures 16 may also bepre-loaded at manufacture or attached to openings around the edge of theframe 10 a to allow fastening of the cover to the adjacent bone ortissue or instrumentation construct.

The instrumentation cover is designed to cover any spinal or other boneinstrumentation installed in the body. The cover can be used for pediclescrew/rod constructs, pedicle screw/plates, bone anchors, or hook androd constructs, such as are commonly used for cervical, lumbar, orthoracic spinal instrumentation. The shield or cover is made of proven,medically safe material, such as GoreTex,™ Dacron,™ polyurethane, or anyother safe, implantable material. The cover may be intended to bepermanently installed, or may be removable in a subsequent surgicalprocedure. The shield or cover preferably is in the form of a solidrectangle or solid oval or other suitable shape and closely fits ontothe instrumentation in a manner analogous to an armrest cover on the armof a chair. It can be made in different sizes or shapes for one-level,two-level, or multi-level instrumentation, and may also be adjustable insize (see further embodiments described below). The shield or coverprevents ingrowth of bone or fibrous tissue into interstices of theinstrumentation because it provides a mechanical barrier to suchintrusion. If the cover needs to be removed, such as when theinstrumentation is to be adjusted, replaced, or removed, it is removedin a similar surgical procedure where it is accessed through an incisionand its lower frame and/or sutures or other fasteners are removed toexpose the instrumentation.

The instrumentation cover may also be made from a molded material, suchas polyurethane foam, or a moldable material such as a non-toxic putty,or from a pliable or stretchable material as long as it is safe forimplantation. The cover is designed to fit or to be adjusted around theinstrumentation so that it covers it snugly and dislodgement ordisplacement is precluded. The cover is typically installed immediatelyafter placement of the instrumentation. Permanent sutures may be used,or absorbable, biodegradable sutures may be used to initially hold thecover in place until healing of the soft tissue surrounding the cover.The instrumentation cover may also be made of a hardenable or gelablematerial such as polycarbonate urethane, elastomeric material, orpolyurethane foam, which can cure in situ and has well-establishedbiochemical compatibility with excellent mechanical strength and elasticproperties.

Another possible material for the cover is a hydrogel or “bioglue” whichis composed of bovine albumin and gluta-aldehyde. This has been used asa chemical adhesive and can be applied around the instrumentation usinga two-chambered cartridge stored at room temperature. It can be injectedinto a form placed over the instrumentation and solidified to 90% solidwithin 30 seconds, and completely in two minutes, without generation ofheat.

In FIG. 2, a second embodiment of the invention is shown in which thecover or shield is formed with a hollow cap or casing 20, similar to theone described previously, and a lower frame 20 a with an open box-likeaperture for accommodating different configurations or sizes ofinstrumentation (here again, pedicle screws 12). Sutures 26 are anchoredto small openings around the edges of the lower frame and used to holdthe cover in place by attachment to adjacent bone areas or tissue.

In FIGS. 3A and 3B, a third embodiment of the cover or shield is formedas a pliable or flexible pouch 30 with drawstrings 36 for tightening thepouch down onto the instrumentation and cinching it around the parts ofthe instrumentation (here again, pedicle screws 12) to hold it in place.The ends of the drawstrings may be wrapped around the instrumentationconstruct or tied to adjacent bone areas or tissue or instrumentationconstruct.

In FIG. 4, a fourth embodiment of the cover or shield is formed with apliable or flexible cap or sheath 40 for encapsulating theinstrumentation, and a lower cinch ring 42 for tightening the cap downaround the instrumentation. The cinch ring has openings 42 a throughwhich a number of adjustable suture strings 46 a tied to the lower edgeof the cap portion 40 are threaded. The cinch ring 42 and cap portion 40are deployed over the instrumentation, and then the loose ends of theadjustable suture strings are pulled through the cinch ring openings 42a to tighten the cap vertically down onto the instrumentation. Twosuture strings 46 b on opposite sides of the cap have ends that areattached to the cinch ring and are not adjustable, as their function isto tie the cinch ring to the cap portion so that it does not slip awayfrom the cap and adjustable sutures while being handled. The cinch ringis in tubular form and is made of a flexible material, such as asynthetic fabric, so that it can also be cinched circumferentially(horizontally) around the lower parts of the instrumentation adjacentthe bone, using drawstrings 48. The suture string and drawstring endsmay be trimmed and tied off to the cinch ring or instrumentationconstruct to prevent accidental removal.

In FIG. 5, a fifth embodiment of the cover or shield has a casing formedwith slidable or displaceable parts or panels 50, 52 for adjustment ofits length around the instrumentation (in the direction of thebidirectional arrow in the figure). Alternatively, the panels may beformed with pleated parts for making the dimensional adjustment. Thepanels may similarly be made adjustable in width or height. Sutures 56attached to the lower frame parts 50 a, 52 a are used to fasten thecover to the instrumentation and/or adjacent bone areas or tissue.

In summary, the bone instrumentation shield or cover is designed toprovide a medically safe physical barrier for implantation betweenprojecting parts of bone instrumentation constructs and surrounding boneand soft tissues. The shield or cover minimizes local irritation orinjury to soft tissues from the instrumentation and also serves as abarrier to ingrowth from bone and/or fibrous tissues. It can be formedin a variety of forms, from solid casing, to semi-pliable sheath-likestructure, to soft pouch or cinch sack. With or without cross clips inplace, the cover can be readily applied from the dorsal aspect over theinstrumentation, then cinched, tied or fastened to the instrumentationadjacent where it enters the bone or to the adjacent bone area oftissue, using suture ties, suture strings, drawstrings and the like. Thecover is made of medically safe material, and can come in various sizesor constructed to be pliable, stretchable, or adaptable with slidable,displaceable or pleated panels. A variety of dimensional arrangementsmay be made for single-level, two-level, three-level and long,multilevel instrumentation constructs.

It is understood that many modifications and variations may be devisedgiven the above description of the principles of the invention. It isintended that all such modifications and variations be considered aswithin the spirit and scope of this invention, as defined in thefollowing claims.

The invention claimed is:
 1. A bone instrumentation cover installed overbone instrumentation adapted to project from the bone of an animalduring bone repair or reconstruction surgical procedure on the animal,the bone instrumentation cover comprising: a hollow cap sized forencapsulating a part of a bone instrumentation which has been installedin bone, the hollow cap adapted for placement in the body of the animaland for encapsulating a part of the bone instrumentation which projectsfrom the bone, the hollow cap providing a medically safe physicalbarrier between the part of the bone instrumentation and the surroundingbone and soft tissue in the animal, the hollow cap being adapted toseparate the part of the bone instrumentation from substantially all ofthe surrounding soft tissue so that the hollow cap prevents ingrowth ofsubstantially all of the surrounding soft tissue through the cap intothe bone instrumentation which projects from the bone, and the hollowcap having a fastener portion securing the cap to the boneinstrumentation portion which projects from the bone.
 2. A boneinstrumentation cover or shield according to claim 1, wherein thefastener portion includes: a cinch ring which is not a part of saidhollow cap, and said cinch ring having one or more draw strings fortightening the hollow cap circumferentially around the instrumentationduring said bone repair or reconstruction surgical procedure, and asuture string for securing the hollow cap to one of adjacent bone andadjacent tissue.
 3. A bone instrumentation cover according to claim 2,further including a plurality of first suture strings, each first suturestring having a first end and a second end, the first ends of the firstsuture strings being fixedly connected to the hollow cap, and the secondends of the first suture strings are threaded through the cinch ring fortightening the hollow cap to the cinch ring with the hollow capextending over the bone instrumentation installed during the bone repairor reconstruction surgical procedure.
 4. A bone instrumentation coveraccording to claim 3, further including a second suture string with afirst end of the second suture string coupled to an edge of the cap andwith a second end of the second suture string coupled to the cinch ring.5. A bone instrumentation cover according to claim 4, further includingan additional second suture string with a first end of the additionalsecond suture string coupled to an edge of the cap and with a second endof the additional second suture string attached to the cinch ring.
 6. Abone instrumentation cover according to claim 1, wherein the hollow capis adjustable in size and is adapted for removal in a subsequentsurgical procedure.
 7. A bone instrumentation cover according to claim1, wherein the hollow cap is adapted to encapsulate substantially all ofthe bone instrumentation adapted to project from the bone after aninitial surgical procedure and is removable in a subsequent surgicalprocedure.
 8. A bone instrumentation cover according to claim 1, whereinthe hollow cap includes pleats adapted for adjustment of one of thelength, width and height of the hollow cap so that the hollow cap fitssnugly around the bone instrumentation.
 9. A bone instrumentation coveraccording to claim 1, wherein the fastener portion includes a lowerframe of the hollow cap provided with an open, box-like aperture shapedfor locking the cap to the bone instrumentation.
 10. A boneinstrumentation cover according to claim 1, wherein the hollow cap ismade of a medically safe material consisting of polyurethane.
 11. Thecombination of claim 1, wherein the hollow cap comprises hydrogel. 12.The bone instrumentation cover of claim 1, wherein the fastener portioncomprises biodegradable sutures.
 13. A bone instrumentation coverinstalled over bone instrumentation adapted to project from the bone ofan animal during bone repair or reconstruction surgical procedure, thebone instrumentation cover comprising: a hollow cap shaped toencapsulate a part of a pedicle screw capable of being installed in bonein the body of a human, the hollow cap being shaped to encapsulate apart of the pedicle screw which projects from the bone and is in thebody of the human, the hollow cap being adapted for placement in thebody of the human during surgery, the hollow cap being adapted toseparate the part of the pedicle screw capable of projecting from thebone in the body of the human from surrounding bone and soft tissue, thehollow cap separating the part of the pedicle screw from substantiallyall of the surrounding soft tissue so that during healing the hollow capprevents ingrowth of bone or tissue through the cap into the part of thepedicle screw which projects from the bone, and a fastener snuglysecuring the cap to the pedicle screw.
 14. A bone instrumentation coveraccording to claim 13, further including sutures that are absorbable invivo and secure the hollow cap to one of adjacent bone and adjacenttissue.
 15. A bone instrumentation cover according to claim 14, whereinthe sutures include a plurality of adjustable suture strings, eachadjustable suture string having a first end and a second end, the firstends of the adjustable suture strings being fixedly connected to thehollow cap, and the second ends of the adjustable suture strings are acinch ring tightening the hollow cap to the cinch ring with the hollowcap extending over the pedicle screw installed during the bone repair orreconstruction surgical procedure.
 16. A bone instrumentation coveraccording to claim 15, further including a non-adjustable suture stringwith a first end of the non-adjustable suture string tied to a loweredge of the cap and with a second end of the non-adjustable suturestring attached to the cinch ring.
 17. A bone instrumentation coveraccording to claim 15, wherein the cinch ring has openings therein, saidcinch ring not being a part of said hollow cap, and said cinch ringbeing a tubular form.
 18. A bone instrumentation cover according toclaim 13, wherein the hollow cap is made of a medically safe materialconsisting of polyurethane.
 19. The combination of a bone implant and abarrier comprising: a bone implant capable of extending from the bone ofan animal, and a barrier material adapted for snugly covering only theportion of the bone implant in the animal which projects from the boneand separating the bone implant from substantially all of thesurrounding soft tissue, wherein the barrier material is a medicallysafe physical barrier between the portion of the part of the boneimplant that is covered and the surrounding soft tissue of the animaland wherein the barrier material prevents ingrowth during healing ofsubstantially all of the surrounding tissue into the bone implant, andmeans for fastening the barrier material to the bone implant.
 20. Thecombination of claim 19, wherein the bone implant is a pedicle screw.21. The combination of claim 19, wherein the barrier material isdesigned to be adjusted around the portion of the bone implant whichprojects from the bone so that it snugly covers the portion of the boneimplant which projects from the bone.
 22. The combination of claim 19,wherein the barrier material is hydrogel.